Liquid fuel injection pump for internal combustion engines



April 12, 1932. G. s. WILKINSON 9 LIQUID FUEL INJECTION PUMP FOR INTERNAL COMBUSTTON ENGINES Filed Oct. 5, 1931 L/ A u L H\ F B I Z, G -s l [oven/ r:

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Af/nys Patented Apr. 12, 1932 UNITED STATES PATENT; OFFICE GEORGE SHAKESPEARE WILKINSON, or LONDON, ENGLAND, AssIeNoE T n. NAPIER & soN LIMITED, OF LONDON, ENGLAND, A COMPANY or GREAT BRITAIN LIQUID FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES Application filed October 5, 1931, Serial Nd. 567,069, and in Great Britain November 7,1930.

in or modification of fuel pumps of the kind forming the subject of prior United States patent application Serial No. 556,928 of 1931.

The above prior United States patent application relates to fuel injection pumps of the kind having one or more relief or inlet ports which are so controlled by the pump plunger or by a separate valve as to render inoperative the earlier and later portions of each plunger delivery stroke and, according to the invention forming the subject of the above patent application, a fuel pump of this kind is provided with means for positively closing the fueldelivery passage at the moment when or immediately after the relief or inlet port is opened to terminate the opera tive part of the delivery stroke.

According tothe present invention a fuel pump of the kind forming the subject of the above patent application is not only provided with means for positively closingthe fuel delivery passage at or immediately after the moment when the relief or inlet port is opened to terminate the delivery period. but also with means for re-opening the delivery passage immediately after closing it so as to relieve the pressure therein.

The invention is particularly applicable to fuel injection pumps in which the pump piston acts both as a plunger and as the valve controlling the inlet or relief port or ports in the cylinder wall and, in this case, the delivery port is preferably also arranged in the cylinder wall and the piston so formed as to close the delivery port positively as or immediately after it opens the relief port to terminate the effective portion of the delivery stroke and also to form communication be-' piston having a helical or like inclined edgeso that by varying the relative rotational po- I sitions of the cylinder and piston, the moment in the plunger delivery stroke at which the relief port is brought into communication with the pump pressure chamber can be varled so as to vary the quantity-of fuel de livered. When the present invention is applied to such a construction the piston or its cylinder is conveniently provided, not onlywith a main relief groove and a delivery groove provided with helical or like inclined edges so that the quantity of fuel injected can be varied by relative rotation between the plunger and the cylinder while ensuring that the delivery passage will always be closed I positively immediately after the relief passage is opened to terminate the delivery period, but also with a subsidiary relief groove having a helical or like inclined edge so as to establish communication between the de- 1 livery passage and a relief or inlet passage,

immediately after the relief passage has been vB and having a delivery port 0 and a combined inlet and relief port D in its circumferential wall. The lower end of the plunger is splined and is surrounded by an internally splined member E so that while the plunger can slide through the member E the rotational position of the plunger relatively to the cylinder can be varied by rocking the member E by means'o'f an arm E thereon.

Bearing on the member E is the upper end of a spring F the lower end of which acts on a collar G which rests on a head Btformed on aprojection B of the plunger B so that the spring tends always to force the plunger out of the cylinder. The cylinder A is supported by a casingH in which slides a guide member J arranged concentrically with and acting on the head B of the-projection B of the I plunger, the lower face of this guide member bearlng on a cam K. on a camshaft-K It will thus be seen that as the camshaft K .ro-}

tates the plunger B will be caused to reciprocate within the cylinder A while by moving the member E by means of the arm E the rotational position of the plunger relatively to the cylinder can be varied. I Formed in the circumferential wall of the plunger is a helical groove L, acting both as a delivery groove and as a relief groove and communicating with the pressure chamber of the pump through a slot L and with a subsidiary helical relief groove L also formed in the circumferential wall of the plunger B. The arrangement is such that the plunger, on the suction stroke, draws in fuel through the combined inlet and relief port D. During the initial part of the delivery stroke of the plunger the port D is uncovered by the piston so that during this portion of the delivery'stroke fuel is returned to the inlet passage through t-he combined inlet and relief port. After the plunger has moved a certain distance on its delivery stroke it covers the port D so that flow of fuel through this port is stopped and fuel is forced through the slot L and groove L and thence through the delivery port 0 which, during this period, communicates with the groove L. Such delivery the groove continues until the upper edge of the groove L uncovers the port D and the arrangement is such that as, or immediately after the port D is uncovered by the upper edge of the groove L, the lower edge of this groove closes the delivery port C so that at the moment when or immediately after communication is reestablished between the pressure chamber of the pump and the relief port, communication between this pressure chamber and the delivery port is cut off.

Immediately after the delivery port C has been positively closed by the lower edge of the combined relief and delivery groove L, it 'is re-opened by the upper edge of the subsidiary relief groove L so as to bring the delivery passage G into communication through 2 and groove L with the combined inlet and relief passage, whereby the pressure in the delivery passage is relieved.

It will be seen that by rockin the plunger by means of the lever E the fiangth of the effective portion of the delivery stroke during which the port D is closed and hence the quantity of fuel injected, can be varied, but that at all rotational settings of the plunger, not only will the delivery port C be closed positively by the lower edge of the groove L at the moment when or immediately after the relief port D is re-opened to terminate the effective' portion of the delivery stroke, but the delivery port C will be re-opened by'the upper edge of the groove L immediately after being so closed.

a It is to be understood that the construction illustrated is given by way of example only and that the means for positively closing the delivery passage at or immediately after the moment when the relief port is opened to terminate the effective part of the delivery stroke and for re-opening the delivery passage immediately after it has been so closed as well as other details ofconstruction may be varied Without departing from this invention. Further, the invention may be applied to fuel injection pumps in which a separate valve controlling inlet or relief ports is operated in timed relation to the piston to render inoperative the earlier and later portions of each plunger delivery stroke.

\Vhat I claim as my invention and desire to secure by Letters Patent is 1. A liquid fuel injection pump for internal combustion engines including in combination a cylinder having a fuel delivery passage and at least one relief port, a plunger adapted to reciprocate within the cylinder, a part acting as a valve to open a relief port during the earlier and later parts of each delivery stroke to render such parts of the stroke inoperative so that fuel is only delivered through the delivery passage during an intermediate operative part of each delivery stroke, means for positively closing the fuel delivery passage as the relief passage is opened to terminate the delivery period, and -means for reopening the delivery passage immediately after closing it so as to relieve the pressure therein.

2. A liquid fuel injection pump for internal combustion engines, including in combination a cylinder having a fuel delivery passage and at least one relief port, a plunger adapted to reciprocate within the cylinder and so formed as to act as a valve which opens a relief port during the earlier and later parts ofveach delivery stroke to render such parts of the stroke inoperative so that fuel is only deliveredthrough the delivery passage during an intermediate'operative part of'each delivery stroke, means for positively closing the fuel delivery passage as the relief passage is opened to terminate the'delivery period, and means for opening the delivery passage immediately after closing it so as to relieve the pressure therein.

3. A li uid fuel injection pump for internal coin ustion engines, including in combination a cylinder having a fuel delivery passage andat least one relief port, a plunger adapted to reciprocate within the cylinder and so formed as to act as a valve which not onl opens a relief port duringthe earlier an later parts of each delivery stroke to render such parts of the stroke inoperative so that fuel is only delivered through the delivery passage during an intermediate operative part of each delivery stroke, but also as a valve for positively closing tlfe fuel delivery passage as the relief port is opened to terminate the delivery period and for reopening the fuel delivery passage immediately after closing it for the purpose set forth.

4. A liquid fuel injection pump for internal combustion engines includin in combination .a cylinder having a relic passage and at least one relief port, a plunger adapted to reciprocate within the cylinder and so formed as to act as a valve to open a relief port during the earlier part of each delivery stroke and having at least one groove therein communicating with the pressure chamber of the pump and provided on the one hand v with an edge which uncovers a relief port during the later part of each delivery stroke so that fuel is only delivered through the de livery passage durin an intermediate operative part of each delivery stroke, and on the other hand with a second edge which covers the delivery passage as the relief groove comes into communication with the relief .port, the said first edge and the said second edge being formed correspondingly helical, while a third similar helical edge uncovers the delivery port immediately after it has been covered by the said second edge, and means for causing relative rotation between the pump plunger and the cylinder whereby the quantity of fuel delivered on each delivery stroke can be varied while maintaining correct timing between the opening of the relief port and the closing and reopening of the delivery passage at the end of the delivery period.

5. A liquid fuel injection pump for inter nal combustion engines including in combination a cylinder having a fuel delivery passage and at least one reliefport, a plunger adapted to reciprocate within the cylinder, a reciprocating cylindrical part acting as a valve not only to open a relief port during the earlier and later parts of each delivery stroke, the edge of the valve which opens the relief port during the later part of each de livery stroke being inclined to the direction of movement of the reciprocating part, but also having correspondingly helical edges one of which closes the delivery passage as the reciprocating member opens the relief port to terminate the effective part of the delivery period while the other reopens the delivery passage immediately after the said first helical edge has closed it, and means for rotating the valve so as to vary the quantity of fuel injected by the pump on each delivery stroke while maintaining correct relative timing between the opening of the relief port, the closing of the delivery passage and the reopening of the delivery passage.

6. A liquid fuel injection pump for internal combustion engines including in combination a cylinder having a delivery passage and at least one relief port, and a plunger adapted to reciprocate within the cylinder and so formed as to act as a valve to open a relief port during the earller part of each delivery stroke, one of suchparts having on the one hand a main relief groove therein mediate part of the deliver which comes into communication with a relief port during the later part of each dehvery stroke so that fuel, is only deliyered through the delivery passage during an ntermediate operative part of each dehvery stroke and on the other hand a delivery groove which communicates with a delivery passage in the other part during at least such interstroke but has an edge which covers the de ivery passage as the relief groove comes into communication with the relief port, and a further subsidiary relief groove an edge of which uncovers the delivery passage immediately after it has been covered by the edge of the dellvery groove, the edge on the main relief -oove which uncovers the relief port, the e ge of the delivery groove which covers the delivery port, and the edge of the subsidiary relief groove which uncovers this delivery port being formed correspondingly helical, and means for producing relative rotation between the pump ,plunger and the cylinder whereby the quantity of fuel delivered 9n each delivery stroke can be varied whlle maintaining correct relative tim1n between the opening of the relief ort and t e closing and reopening of the de lvery passage.

In testimony whereof I have signed my 

